Logistic Characterization of Left Ventricular Isovolumic Pressure-Time Curve.
نویسندگان
چکیده
منابع مشابه
Differential laws of left ventricular isovolumic pressure fall.
An attempt has been made to test for a reliable method of characterizing the isovolumic left ventricular pressure fall in isolated ejecting hearts by one or two time constants, tau. Alternative nonlinear regression models (three- and four-parametric exponential, logistic, and power function), based upon the common differential law dp(t)/dt = - [p(t)-P ]/ tau(t) are compared in isolated ejecting...
متن کاملPostextrasystolic left ventricular isovolumic pressure decay is not monoexponential.
OBJECTIVE The relationship between the left ventricular (LV) relaxation time constant and early diastolic filling is not fully defined. This study provides additional evidence that LV isovolumic pressure fall in the normal intact heart in response to certain interventions is not adequately described by a model of monoexponential decay and that its relationship to filling is complex. METHODS A...
متن کاملQuantification of incomplete left ventricular relaxation: relationship to the time constant for isovolumic pressure fall.
We initially found that the fall in left ventricular pressure during isovolumic relaxation is exponential and therefore characterized by a time constant (T). To the extent that isovolumic pressure fall reflects myocardial events during relaxation, T indexes the time course of relaxation of the left ventricle. In isolated canine hearts sudden beat to beat loading changes from isovolumic to eject...
متن کاملTemperature-dependent inotropic and lusitropic indices based on half-logistic time constants for four segmental phases in isovolumic left ventricular pressure-time curve in excised, cross-circulated canine heart.
Varying temperature affects cardiac systolic and diastolic function and the left ventricular (LV) pressure-time curve (PTC) waveform that includes information about LV inotropism and lusitropism. Our proposed half-logistic (h-L) time constants obtained by fitting using h-L functions for four segmental phases (Phases I-IV) in the isovolumic LV PTC are more useful indices for estimating LV inotro...
متن کاملPhysical determinants of left ventricular isovolumic pressure decline: model prediction with in vivo validation.
The rapid decline in pressure during isovolumic relaxation (IVR) is traditionally fit algebraically via two empiric indexes: tau, the time constant of IVR, or tau(L), a logistic time constant. Although these indexes are used for in vivo diastolic function characterization of the same physiological process, their characterization of IVR in the pressure phase plane is strikingly different, and no...
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ژورنال
عنوان ژورنال: The Japanese Journal of Physiology
سال: 1995
ISSN: 0021-521X
DOI: 10.2170/jjphysiol.45.535